Nuclear whistleblower Mordechai Vanunu will be barred from leaving Israel for a year to prevent him from spilling more state secrets once he completes his 18-year jail term today.

The ban was due to "a tangible danger... that Vanunu wishes to divulge state secrets, secrets that he has not yet divulged and which have not been previously published," a Defence Ministry statement said.

Vanunu's brothers voiced fears for his safety during the year he will be forced to stay in Israel, where the former nuclear technician is widely despised as a traitor for revealing Israel's nuclear secrets to a British newspaper.

Appealing to Britain to offer Vanunu sanctuary, his brother Meir told BBC radio: "If something happens to my brother, the blood and responsibility... is also on the British government."

Vanunu's brothers rented him a luxury seaside apartment in Jaffa, southern Tel Aviv, close to a church where the 49-year-old Christian convert can attend prayers. The location was supposed to have been secret but was leaked to the media.

Vanunu will be required to tell police if he stays overnight anywhere else. He must not approach border exits or talk to foreigners without prior approval for at least six months.

Security services will be keeping a close eye on Vanunu. "The keys are in Vanunu's hands. The reissuance of the restrictions depends on the steps he takes, on his conduct and on future violations of the law," the Defence Ministry said.